1. Field of the Invention
The present invention relates generally to methods of controlling actuator assemblies and, more particularly, to an actuator assembly control method which is able to control the actuator assembly according to conditions of vehicle velocity and a steering angle or the vehicle velocity and a steering angular velocity, thus reducing energy consumption, thereby increasing the efficiency of the actuator assembly.
2. Description of the Related Art
As well known to those skilled in the art, a suspension system must satisfy basic requirements of providing controllability and stability of a vehicle when turning, braking and driving. Positioning of wheels according to suspension geometry serves as a very important factor to satisfy these basic terms. Particularly, camber and toe largely affect stability of the vehicle when turning and driving straight. This is intimately associated with roll of the vehicle body.
Actuator assemblies for suspension systems, which are capable of appropriately controlling camber and toe according to the driving conditions of the vehicle, were proposed in Korean Laid-open Publication No. 2003-0017668 and U.S. Pat. No. 4,835,714.
FIG. 1 is a perspective view showing the conventional actuator assembly for suspension systems of U.S. Pat. No. 4,835,714. As shown in FIG. 1, in the actuator assembly of U.S. Pat. No. 4,835,714, an actuator 209 has a hinge shaft 209 which is coupled to a sub-frame by a hinge, and two gears 213 and 215 to be driven by a motor 211. A rod 224 is rotatably coupled at a first end thereof to the actuator 209. A knuckle 219 is rotatably coupled to a second end of the rod 224. The operation of the actuator assembly having the above-mentioned construction is as follows. When the motor 211 of the actuator 209 is driven, the gears 213 and 215 are rotated. Then, the hinge shaft 214 rotates in a predetermined direction. The rotation of the hinge shaft 214 is converted into a linear motion of the rod 224. Then, the reference length of the knuckle 219 coupled to the rod 224 is changed. As a result, the knuckle 219 is rotated, so that a toe angle is changed.
However, the above-mentioned actuator assembly for suspension systems has the following problems.
When considering the geometry, the change in the toe angle by the operation of the actuator assembly is effective only when bump of the wheels occurs. Otherwise, when bump of the wheels does not occur, although the actuator is operated, the toe angle is not changed. Therefore, the conventional actuator assembly is problematic in that energy consumption occurs due to pointless operation of the actuator.